Diamond bit protector



July 7, 1953 1'. c. MATHr-:ws l y 2,644,672

I DIAMOND BIT PROTECTOR Filed Jan. 29. '1951 2 sheets-sheet 2 Patented` July 7, 1953 UNITED "STATES PATENT .f I 'i ."v.2,644,672 .f v v ,A vpmi/.loup BIT PROTECTOR v i Tea c. Mathews, Fairbanks, Territory of Alaska v Applicationianuary 29,1951, seria1No.208.,264

My invention relates to diamond bit protectors.

In diamond drilling operations, a bit is used and particularly during the initial operation` of the bit at the bottom of the hole, the diamonds may be severely damaged. In loweringjthe bit, the side surfaces of the diamond-embedded matrix strike the walls of the Ybore holeand the exposed facets of the diamonds are broken. After the bit is on the bottom, and in spite of circulation, there may remain loose junk or` debris. This does not readily grind up, ybut instead rolls and strikes thecuttingfacets breaking oi these portions vand thus impairing, "if 4`not Vcompletely ruining the bit, before the drilling operation has actually started. Accordingly then, included in' the objects of my invention are: l

First, to provide a means, as well vasa method,`

Figure 6 is a sectional view similar to Figure 5 showing a modified form of my protector yinwhich the side walls of the bit matrix are covered;

, form of my protector.

Figure 7 is a partial sectionalview, partialelevational view of a large diameter diamond'drill such as used in oil well drilling, showing another Figure 8 is a fragmentary sectional view of anlother type of bit vshowing my protector thereon.

' vFigure 9 "is a fragmentary; end

screw-threaded at its upper end for attachment of protecting a diamond bit during'the course of' lowering the bit andY particularly during lthe initial drilling operation after bottomingy the bit, so that damage to the bit is materially reduced.

Second, to provide a diamondY bit protector formed of thermo-plastic material VorV of a'nalleable material softer thanA the matrix comprising ythe tip ofthe bit, aswell 'as softer'than the formation encountered by the bit, so that upon the application of pressure exerted by the'bit against the bottom ofthe bore hole,v the protector is caused to deform or otherwise Vlowso as to embed Aor consolidate any loose material and form therewith a solid matrix, the protectorbeing so attached to the bit that uponinitial rotation under pressure, the protector strips from'the' bit so that it may be ground upandwashed from the bore hole by circulation.`

With the above and 'other objects in'yiew* as for a drilling string not shown. Molded 'or-cast on the lower endof the body 2 or formed thereon "by a sintering or welded technique is an'annular matrix 3. The matrix comprises a bondingA material and diamond or silicon carbide'fragment's, the exposed facets of which providefcutting'or attrition edges. The cutting ,tipA of Athe Vbit .is

vusually interrupted by groovesand slots LtoV facilitate circulationof fluid from the-insidedrili string and bit around the under side of" the.; bit and upwardly through the bore hole. Y i y My protector is inthe form` of .ringt 5 e of substantial thickness having anvinternal diameter and an external diameter corresponding to that ofthe bit tip. Inasmuch as the bit tip Vis usually flat, the upper surface of .thelprotetcr is likewise flat. Inany. case, the `upper surface of the protector is shaped so asuto conform to the cutting surface ofthe bit. ItisV preferredthat the protector, bridge the circulation. channels `4.

` amino acid related plasticssuch as nylonfpolyf.

may appear hereinafter, reference is directed to A the accompanying drawings in;which:

Figure 1 is a side view of a typicaldamond bit with my protector shown thereon.

Figure 2 is a similar `view but with the protector shown spaced from the bit. Figure 3 is a perspective View ofthe protector.

Figure 4 isa transverse sectional View through 4 4 of Figure 1.

Figure is an enlarged. fragmentary longituv styrene, acetate, and. acetate butyratefmay-be used.

, In selecting the material the temperature conditions existing at the bottom of the bore hole and the pressures employed must be rtaken int4 count.'r 7:: I. l n

The protector is pressedy on to the v bit so as to embed'the protruding-portions diamonds, in addition, fa`4 cement 'indicate -byf-S is employed. Actually the cement in mes n c'as'es is a solvent for the plastic-materialeomprising the protect0r.-- Alternately-ther protector maybe castv or-molded on the bit.

Still further, the Y protector may be I'provided grooves 0r A number of*thermoplastic'materials are l I 3 the bit matrix as shown in Figure 6. It should be noted however, that this lip must be relatively thin in order not to interfere with the lowering of the Vbit into the bore hole. Y

My protector is employed as follows:

The bit with the protector in place is lowered into the well bore, the driller may, before or after a preliminary circulation, set the full weight on bottom to cause plastic ow of the protector over and around any jun or loose debris which may be present in the bottom of the bore hole. The drill string is then picked up until a normal drilling weight is applied. The bit is then rotated slowly at first preferably in conjunction with a reduced circulation pressure. As soon as it is feasible to assume that the protector has been cornpletely ground up, drilling may continue in a conventional manner. Y

The'initial pressurre'applied to the protector so thoroughly embeds the protector in the debris at the bottom of the bore hole 'as to form a solid matrixy firmly holdingtheY plastic so that on rotation of the bitor application of fluid pressure through the bit or a combination of rotation and fluid pressure, the protector'strips free ofthe bit intact.

Y the end face of said bit and lof such thickness l' ture when subjected to shock loads; said protc-f tor initially covering the end of saidbit during its descent into a well bore; said protector adapted to be compressed between the bit and the bottom of the well bore, thereby to iiow around and embed debris at the bottom of the well bore; said ing: a disk of malleable plastic material capableV of plastic ilow under compression but friable under shock load-s, vsaid material initially secured to asto embed debris at the bottom of the well bore when subjected to compression between the :bit and the bottom of the well bore, thereby to form Fluid pressurejis'utilized asan aid in. stripping' f the protector from thefbitby first applying' excess weight to the bit, when on bottom, toernb'ed the loose particles, then, just before reducing the weight to that required for drilling, to apply excess uid pressure. As the weight is reduced, the excess fluid pressure acts to lift the bit off bottom, creating a vertical Vibrationwhichloosens the protector. The fluid pressure is then returned to normal and drilling is resumed. Y Y Reference is now directed to Figure 7. Here illustrated is a larger type of vbrit as Yused in oil welldrilling. The bit H is adapted lfor, screwthread connection to a drilling string i2. The lower end of the bit is reduced internally to form a cutting head I3 and imbedded with diamond particles or similar cutting.materialfifL---y -Water passages l5 extend axially through the cutting head and intersects its lower surface.

AIn conjunction with this bit construction,Y my protector is shown as a vdisk IE vcoveringfthe 'end of the bit and including a thin covering ITon the external surface of the cutting head. If desired, the disk IB may have one or more ports 'I8 -of sufficiently small area to establish a pressure differential across the disk on circulation of Yfluid downwardly through the drilling string so as to be forced off, when desired.

Reference is directed to Figures 8 and 9. Here the bit is similar to the construction shown in Figure 'Twith the addition of cross slots I9 intersecting the water passages l5. The protector disk 2l) is shown which is similar to the disk lB except that the central opening y2| coincides with the Vinternal diameter of the drilling head.

It is preferred that the protector be transparent so that the cutting material exposed at the surface of the bit maybe inspected to determine Iits character and condition.

Having fully described my invention,V it is to be a ,core'cutting bitA and softer lthan the` material,

well', loose y'debris present in the 'bottom with the debris al grindable matrix; said disk adapted on rotation of said bit Vto strip therefrom' .j Y f ing: a disk of 'material softer than said bitand softer than the vmaterial encountered by-said bit; said disk being capable" of plastic flow under compression but fracturable'under shock loads; said diskinitially secured toand covering the end of the bit and of' such thickness' that on being cornthe bit and thebottom ofthe of the Well is` embedded and held by the disk; said disk adapted on rotation of said bit to strip therefrom and form with .the debris a heterogeneous grindablemass.

Ll.'.A1 `rotector as set forth in claim l, wherein: said protector istransparentto expose toview the surface of said bit. f

5. A protector as set forthin claim 3, wherein: said disk is initially transparent to expose to view thesurface of said bit.

pressed' between 6. A protector for annular diamond core cut- .ting`bit`s, involving: a disk of material'softer than encountered by said bit, and capable of plastic flow under pressure,v said'disk being `initially secured to and Covering thevend of's'aid bi1; andof such thickness'as to embed loose debris presentat the bottom of a bore holev to form with such debris a Yg'rindable matrixj and an annular covering of saidmaterial initially roverlying the external cuttingsur'faceof saidlbit. j f

v l7.f A protector' for annularv diamond coreV cutting bits, involving: 'a disk of material softer than a core cutting bit and softer than the material encounteredfby said bit, and capable of plastic ow 'under pressure, said disk being initially secured to and covering theend of said bit, and of suchl thickness as to rembed loose debrisr present at'the bottom of a bore hole toform with such debris a grindable matrix; and an annular covering of said materi-alinitially overlying the ex-A ternal cutting surfaceof said bit,V said protector A Y disk adapted tobe forced kfrom said bit on flow of circulating fluid through said bit. f

understood that I do not wish to be limited-to the Y `8.y A protector asset forth inclaim fwh'erein said disk is initially transparent to expose to viewk the svurfaceof-saidbit. l. y K

neferiiicesciteapin the me of this patentd UrirrEn srTEs PATENTS.: r1 Number. l Date;

3.' A protector for on diamond bits, involv- 

